Apparatus comprising an optically transparent sheet and related methods

ABSTRACT

An apparatus includes an optically transparent sheet having an electrically conductive layer, an electrode element, and electro-vibration circuitry configured to provide a time-varying voltage signal across the electrically conductive layer and the electrode element so as to cause a user to experience electro-vibration in a first body part of the user when the first body part is moved across an exterior surface of the optically transparent sheet while a second body part of the user is in contact with the electrode element.

FIELD

The invention relates to apparatuses comprising an optically transparentsheet, the optically transparent sheet comprising an electricallyconductive layer.

BACKGROUND

It is known to provide tactile feedback to users of touch screendisplays. Methods for providing tactile feedback include vibration ofthe device in which the to touch screen display resides. Such vibrationmay be provided by, for example, piezoelectric or mechanical actuators.

SUMMARY

This specification describes an apparatus comprising an opticallytransparent sheet comprising an electrically conductive layer, anelectrode element, and electro-vibration circuitry configured to providea time-varying voltage signal across the electrically conductive layerand the electrode element so as to cause a user to experienceelectro-vibration in a first body part of the user when the first bodypart is moved across an exterior surface of the optically transparentsheet while a second body part of the user is in contact with theelectrode element.

This specification also describes an apparatus comprising an opticallytransparent sheet comprising an electrically conductive layer, anelectrode element, a detector configured to detect a user touch input onthe optically transparent sheet by detecting a current in theelectrically conductive layer, and electro-vibration circuitryconfigured to provide a time-varying voltage signal across theelectrically conductive layer and the electrode element in response todetecting a user touch input on the optically transparent sheet.

This specification also describes a method comprising detecting a touchinput on an optically transparent sheet by detecting an electric currentin an electrically conductive layer, the electrically conductive layerconstituting part of the optically transparent sheet, and in response todetecting a user touch input on the optically transparent sheet,providing a time varying voltage signal across the electricallyconductive layer and an electrode element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of an exemplary embodiment ofan apparatus for providing tactile feedback to a user of a portableelectronic device;

FIG. 2 is a schematic cross sectional view of a portion of the apparatusof FIG. 1 for illustrating the phenomenon of electro-vibration;

FIG. 3A is a plan-view of a portion of the apparatus of FIG. 1;

FIG. 3B is a flow-chart illustrating an operation of the apparatus ofFIG. 1;

FIG. 4 is an enlarged schematic view of a hydrophilic layer of theelectro-vibration apparatus of FIG. 1;

FIG. 5 is a schematic perspective view of another exemplary embodimentof an apparatus for providing tactile feedback to a user of a portableelectronic device;

FIG. 6 is a schematic cross-sectional view of another exemplaryembodiment of an apparatus for providing tactile feedback to a user of aportable electronic device;

FIG. 7 is plan-view of a mobile communication device including analternative embodiment of the apparatus of FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 is a schematic cross-sectional view of an embodiment of anelectro-vibration apparatus 1 for providing tactile feedback to a userof a portable electronic device. The electro-vibration apparatus 1comprises a transparent electro-vibration film 10 which is suitable foroverlying a display panel 12, for example an LCD display panel, of anelectronic device (not shown in full in FIG. 1). The transparency of thetransparent electro-vibration film 10 allows images displayed on thedisplay panel 12 to be seen clearly by a user through the transparentelectro-vibration film 10.

The electro-vibration apparatus 1 also comprises a rear electrode 14 andfeedback circuitry 16. The feedback circuitry 16 is in electricalconnection with the transparent electro-vibration film 10 and the rearelectrode 14. The function and operation of the feedback circuitry 16will be described in some detail later in this specification. Thefeedback circuitry 16 is adapted to receive power from a power supply18, for example, a battery of a mobile phone. Also, as will be discussedin more detail later in this specification, the feedback circuitry 16may receive data signals from the processor 20 which controls thedisplay screen, for example, the processor of a mobile phone. The rearelectrode 14 is in electrical communication with the transparentelectro-vibration film 10. The rear electrode may comprise any suitableconductive material, for example films of silver, gold, nickel, copper,aluminium, carbon or metallic coated polymers.

The transparent electro-vibration film 10 comprises a substrate layer102. When the transparent electro-vibration film 10 is overlying adisplay panel 12, the to substrate layer is adjacent a display, orupper, surface 122 of the display panel 12. It will be appreciated,however, that additional transparent layers (not shown) may beinterposed between the substrate layer 102 and the display surface 122of the display panel 12. Such interposing layers may include an adhesivelayer (not shown) for adhering the transparent electro-vibration film 10to the display surface 122 of the display panel 12. The substrate layer102 may comprise, for example, a polymer film, or a glass or plexiglasssheet. The substrate layer 102 may have a thickness in the range of, forexample, 10 nm to 100 μm. Alternatively, the substrate layer 102 mayhave a thickness in the range of, for example, 1 μm to 100 μm. Thesubstrate layer may be flexible.

The transparent electro-vibration film 10 further comprises a conductiveelectrode layer 104. The conductive electrode layer 104 is provided atopthe substrate layer 102. That is to say, the conductive electrode layer104 is provided adjacent a surface of the substrate layer 102 that isthe least proximal to the display panel 12, when the transparentelectro-vibration film 100 is in position atop a display panel 12. Theconductive electrode layer 104 comprises a transparent electro-vibrationelectrode 1040 and plural contact electrodes 1042.

The transparent electro-vibration electrode 1040 comprises a layer oftransparent electrically conductive material. The transparentelectro-vibration electrode 1040 may be provided over the entire surfaceof the substrate layer 102. Alternatively, the transparentelectro-vibration electrode 1040 may be provided atop only part of thesurface of the substrate layer 102. For example, the transparentelectro-vibration electrode 1040 may be provided atop a middle region(not indicated on the Figures) of the surface of the substrate layer102, but not on a perimeter region (not indicated on the Figures) of thesurface of the substrate layer 102. The transparent electro-vibrationelectrode 1040 comprises a layer of Indium Titanium Oxide (ITO). Thethickness of the transparent electro-vibration electrode 1040 may be,for example, in the range of several hundred nano-meters, for example,100 nm to 1. It will be appreciated that the transparentelectro-vibration electrode may alternatively comprise, for example, acarbon nanotube (CNT) network, a thin layer, of for example 10 nm, ofgold, silver or aluminium, or any other suitable transparent conductor.

The plural contact electrodes 1042 are distributed around the perimeterof the transparent electro-vibration electrode 1040. According to someembodiments, including that depicted in FIG. 5, the plural electrodesare located at the corners of the transparent electro-vibrationelectrode 1040. In such embodiments, the number of contact electrodes isdependent on the shape of the transparent electro-vibration electrode1040. In embodiments such as that depicted in FIG. 3A and FIG. 5, wherethe transparent electro-vibration electrode 1040 (and also thetransparent electro-vibration film 10 itself) is rectangular, there arefour contact electrodes 1042-1 to 1042-4 (see FIG. 3). One contactelectrode 1042 is located at each corner of the transparent vibrationelectrode 1040. The provision of the contact electrodes 1042 allow anelectric signal to be provided, via the contact electrodes 1042, to thetransparent electro-vibration electrode 1040. Also, as will be discussedin more detail later, the provision of the contact electrodes allows thetransparent electro-vibration film 10 to be used in detecting andidentifying a location of an incident touch input. The plural contactelectrodes may comprise, for example, trace amounts of silver, gold,aluminium or copper.

The transparent electro-vibration film 10 comprises also a dielectriclayer 106 located atop the conductive electrode layer 104. That is tosay, the dielectric layer 106 covers the conductive electrode layer. Theconductive electrode layer 104 is thus interposed between the substratelayer 102 and the dielectric layer 106. The dielectric layer 106comprises a transparent material. The dielectric layer comprises ahigh-K dielectric material. The high-K dielectric material may include,but is not limited to, hafnium oxide, aluminium oxide or titaniumdioxide. The dielectric layer may have a thickness in the range of, forexample, 100 nm to 1 μm. The dielectric layer 106 prevents directgalvanic contact between the conductive electrode layer 104 and a user'sfinger when placed on an external surface of the transparentelectro-vibration film 10.

Atop the dielectric layer 106 is provided a protective layer 108. Theprotective layer 108 protects the layers beneath it, such as thedielectric and conductive electrode layers 104, 106 from damage byexternal influences, including water and other contaminants. Theprotective layer 108 also has anti-scratch properties and/oranti-reflection properties. The protective layer 108 may comprise, forexample, diamond arc, a diamond-like carbon coating or a hard polymer.The protective layer 108 may have a thickness in the range of, forexample, 1 nm to 100 nm. Alternatively, the protective layer 108 mayhave a thickness in the range of, for example, 10 nm to 50 nm.

Provided adjacent, or atop, the protective layer 108 is a hydrophiliclayer 110. The hydrophilic layer 110 constitutes the external surface ofthe transparent electro-vibration film 10. The hydrophilic layer 110,the construction and operation of which will be described later withreference to FIG. 4, removes moisture from the to user's finger. As willbe discussed, this improves the operability of the transparentelectro-vibration film 10 to provide electro-vibration to the user.

The phenomenon of electro-vibration, and the way in which theelectro-vibration apparatus 1 operates to provide electro-vibration to auser, will now be described with reference to FIG. 2. FIG. 2 is aschematic cross-sectional view of a portion of the electro-vibrationapparatus of FIG. 1. For illustrative purposes, the dielectric,protective and hydrophilic layers 106, 108, 110 are shown as a compositedielectric layer.

Electro-vibration is an effect that occurs when a first body part of auser, for example a finger tip, is slid along a conductive surface and asecond body part of a user, for example a palm of a hand, is inelectrical communication (which includes being in contact via ground)with a second conductive element, while a time-varying potential isapplied across the conductive surface and the second conductive element.

The human skin is comprised of many different layers, the outermost ofwhich is the stratum corneum. The stratum corneum has high electricalimpedance compared to the deeper, relatively conductive layers of theskin. Thus, when a finger tip is placed on a conducting surface, thestratum corneum could be considered the dielectric of a capacitor, withthe plates being the conducting surface and the relatively conductivedeeper layers of the skin. When a potential is applied across twocapacitor plates which are moveable relative to one another, thedielectric between the plates experiences a compression force due to theelectrostatic attraction between the two plates. Consequently, when apotential is applied across the conductive surface and the secondconductive element, which is electrically connected to the relativelyconductive layer of skin of the finger tip, via the second body part andthe body itself, the stratum corneum is compressed slightly. There areno nerve endings in the stratum corneum and thus this compression is notsensed.

Let us now consider this compression force with reference to FIG. 2. InFIG. 2, a first body part, for example a first finger 20, whichcomprises the stratum corneum 202 and the deeper relatively conductiveskin layers 204, is in contact with the surface transparentelectro-vibration film 10, and a second body part 22, for example asecond finger or a palm, is in contact with the rear electrode 14. Atime-varying signal 24 provided by the feedback circuitry 16, is appliedacross the conductive electrode layer 104 of the transparentelectro-vibration film 10 and the rear electrode 14. The first andsecond body parts 20, 22 are in electrical connection via the body 26 ofthe user. If an AC signal is used for the time-varying potential, theelectrical loop formed by the first and second body parts 20, 22, thebody 26 of the user, feedback circuitry 16, the transparentelectro-vibration film 10 and the rear electrode, may be termed a closedAC electric loop.

At a point in time, the time varying potential results in anelectrostatic attraction between the deeper relatively conductive skinlayers 204 and the conductive electrode layer 104. As such, the stratumcorneum 202 experiences a compression force, f_(e)(t). The compressionforce, f_(e)(t), is dependent on the magnitude of the time-varyingpotential, the dielectric constants of the stratum corneum 202 and thecomposite dielectric layer 106, 108, 110. As mentioned above, thiscompression cannot be sensed by the user.

Now let us consider what happens when the first finger is slid acrossthe surface of the transparent electro-vibration film 10. The frictionalforce, f_(f)(t), on the finger tip is given by:f _(f)(t)=μ[F _(u) +f _(e)(t)]

where μ is the coefficient of dynamic friction and F_(u) is the normalforce applied by the user.

The frictional force, f_(f)(t), results in a shear force which deformsthe skin and which is detectable by the nerves in the skin. As thecompression force, f_(e)(t), experienced by the stratum corneum 202varies with the time varying potential so too does the shear force,f_(f)(t). As such, as the time varying potential provided by the feedback circuitry 16 oscillates at a particular frequency, so too does theshear force. This oscillating shear force is sensed as a vibration ofthe finger tip and can be termed electro-vibration.

Electro-vibration is detectable by a user in a frequency range ofapproximately 0.5 Hz to 5000 Hz. The detection threshold for thezero-to-peak amplitude of the time varying potential has been found tobe as low as 12V (at 50 Hz).

Referring back to the electro-vibration apparatus 1 of FIG. 1, thefeedback circuitry is operable to provide a time varying potentialacross the conductive electrode layer 104 and the rear electrode. Theperceived amplitude of the electro-vibration signal may be adjustable bythe user of the electro-vibration apparatus 1. For example, the user maybe able to select a voltage for the electro-vibration signal in therange of 10V to 200V. In this way, the user can set the feedback to alevel which is most suited to them. The feedback circuitry may comprisecharge limitation circuitry (not shown in the Figures), which allows thevoltage of the feedback signal to be relatively high by limiting thetotal charge per pulse, and thus also the current, to a safe level. Thecharge per pulse is limited to a level which is below the threshold forproviding electrocutaneous nerve stimulation, for example a chargeequivalent to current of 1 mA. Electrocutaneous nerve stimulation isdirect stimulation of the nerve in the skin as a result of a currentpassing therethrough.

The electro-vibration apparatus 1 is also operable to determine theincidence and location of a touch input. With a closed loop system, suchas that shown in FIGS. 1 and 2, it is possible to measure the resistanceof a path on the transparent electro-vibration electrode 1040 between afinger 20 incident on the transparent electro-vibration film 10 and anyof the contact electrodes. By determining the resistances of the pathsfrom the finger 20 to each of the contact electrodes 1042, it ispossible to determine the location of the finger. This technique fordetermining a location of the touch input may be termed the 4-Rmeasurement technique.

An exemplary operation of the electro-vibration apparatus 1 to providetactile feedback to the user of the portable display device whichincludes the electro-vibration apparatus 1 will now be described withreference to FIGS. 3A and 3B.

FIG. 3A is a schematic plan view of the transparent electro-vibrationfilm 10 of the electro-vibration apparatus 1 overlying the displayscreen 12. Each of the contact electrodes 1042-1 to 1042-4 iselectrically connected to the feedback circuitry to 16. The feedbackcircuitry 16 is thus operable to determine the resistances of the pathsbetween a touch input 30 and each of the four contact electrodes 1042.In this way, the feedback circuitry 16 determines the location (X_(T),Y_(T)) of the touch input 30.

The feedback circuitry 16 is in data communication with the processor20, which controls the display panel 12. The feedback circuitry 16 isoperable to receive from the processor 20 data identifying locations onthe display panel 12 of objects displayed by the display panel 12. InFIG. 3, the display panel is displaying four objects, ICON A 32, ICON B34, ICON C 36 and ICON D 38. Icons A to D are located at locations(X_(A), Y_(A)), (X_(B), Y_(B)), (X_(C), Y_(C)) and (X_(D), Y_(D))respectively. Thus, data identifying these locations is received by thefeedback circuitry 16 from the display processor 20.

The flow chart of FIG. 3B illustrates an exemplary operation of thefeedback circuitry 16 to provide feedback to a user. In step S3-1, thefeedback circuitry 16 determines if a touch input is detected on thetransparent electro-vibration film 10. This is determined based on thefeedback circuitry 16 detecting that the circuit comprised of thetransparent electro-vibration film 10, the rear electrode 14 and thebody 26 of the user has been completed.

If a touch input is not detected, the operation returns to step S3-1 andawaits detection of a touch input. If an input is detected, theoperation proceeds to step S3-2 and determines the location of the input(X_(T), Y_(T)). This is determined using the 4-R measurement techniquediscussed above. Once the location (X_(T), Y_(T)) of the touch input isdetermined, the operation proceeds to step S3-3.

In step S3-3, the operation determines if the location of the touchinput (X_(T), Y_(T)) 30 is equal to the location (X_(A), Y_(A)), (X_(B),Y_(B)), (X_(C), Y_(C)), (X_(D), Y_(D)) of one of the icons 32, 34, 36,38 displayed on the display panel 12. If the location (X_(T), Y_(T)) ofthe touch input is not equal to the location of the one of icons 32, 34,36, 38, the operation returns to step S3-1. If, however, the feedbackcircuitry determines that the location of the touch input (X_(T), Y_(T))is equal to the location of one of the icons the operation proceeds tostep S3-4.

In step S3-4, following a positive determination that the location ofthe touch input (X_(T), Y_(T)) is equal to the location of one of theicons, the feedback circuitry switches on an electro-vibration signalwhich is provided across the conductive electrode layer 104 and the rearelectrode 14. This signal may comprise, for example, a time-varyingpotential having a frequency in the range of, for example, 5 Hz to 500Hz and having a zero to peak amplitude of, for example, 12 V. A suitablepulse shape for the electro-vibration signal is, for example, a pulsehaving a very rapid rise time, for example 1-2 ms, and having arelatively short duration, for example 10 ms. Such pulses may berepeated with basic frequency (5-500 Hz). The use of a pulse-shape suchas this limits the total charge transmitted through the skin. In thisway, as a user slides their finger onto and over an area of thetransparent electro-vibration film 10 corresponding to a displayed icon,electro-vibration will be experienced.

Following step S3-4, the operation proceeds to step S3-5. In step S3-5,the feedback circuitry determines if the touch input is still detected.In the event of a negative determination, the operation proceeds to stepS3-6. In step S3-6, the feedback circuitry 16 switches off theelectro-vibration signal. Thus, if a user input is no longer detected,the electro-vibration signal is switched off.

If in step S3-5 it is determined that a touch input is still incident,the electro-vibration signal remains switched on and the operationproceeds to step S3-7. In step S3-7, the feedback circuitry 16determines the location of the touch input. Following this, in stepS3-8, the feedback circuitry determines if the location (X_(T), Y_(T))of the touch input is equal to the locations of one of the icons.Following a positive determination, the electro-vibration signal remainsswitched on and the operation returns to step S3-5. If, in step S3-8, itis determined that the location (X_(T), Y_(T)) of the touch input is notequal to the location of one of the icons, the operation proceeds tostep S3-6 in which the feedback circuitry switches off theelectro-vibration signal. Thus, the user will no longer sense theelectro-vibration.

Following step S3-6, the operation returns to step S3-1 and awaitsdetection of a touch input.

In the above operation, the locations of the touch input and the iconshave been denoted as a single coordinate (X, Y). It will be understoodhowever, that, in practice, depending on the resolution of thetransparent electro-vibration film 10 and the display, the touch inputand icons may instead have a range of associated coordinates. Thus, insteps S3-3 and S3-8, the feedback circuitry may instead determine if oneof the coordinates denoting touch input is within one of the coordinateranges identifying the icons. In this way, the electro-vibration signalmay be switched on when the user crosses from outside to inside aboundary (not labelled) defining an icon, and may be switched off whenthe user crosses from inside to outside the boundary.

In addition to the locations of the icons, the display processor 20 mayalso provide the feedback with other information about each icon. Suchinformation may include, for example, frequency of the use. Thus, thefeedback circuitry 16 may provide a different electro-vibration signal,for example a signal having different frequency or potential, for thoseicons that are more commonly selected than for those which are lesscommonly selected.

Displayed icons may comprise different colours. An indication of thecolour may be passed from the display processor 20 to the feedbackcircuitry 16. Thus, the feedback circuitry 16 may provide a differentelectro-vibration signal having, for example, a different frequencydependent on a colour of the icon. In this way, the electro-vibrationsignal associated with a red icon may have a lower frequency, forexample, 100 Hz, than that associated with a blue icon, for example, 250Hz.

In addition to identifying the location of a touch input for the purposeof providing electro-vibration to a user, the feedback circuitry 16 mayalso be used to detect input commands, for example the selection of oneof the icons displayed on the display. Thus, if the feedback circuitry16 determines that the location of a touch input corresponds to thelocation of one of the icons 32, 34, 36, 38, the feedback circuitry 16may send a signal to the processor 20 of the portable device indicatingthat an input in relation to a particular icon has been received. Uponreceiving this signal, the processor 20 may perform an operationrelating to the icon selected.

As discussed, the phenomenon of electro-vibration results from aninduced change in the frictional force between the user's finger and thesurface of the transparent electro-vibration film 10. Thus, by changingthe potential and frequency of the electro-vibration signal, it ispossible to simulate to the user the perception of touching variousdifferent textures of surface. For example, by increasing the potentialto from, for example, 20 to 30V), the change in frictional force will begreater, and thus the user will perceive a more pronounced effect, whichmay feel like a coarser texture (i.e. perceived protuberances willappear larger in height). Similarly, by using a higher frequency signal,for example 700 Hz instead of 300 Hz), the user will perceive a texturehaving a greater number of protuberances per unit distance. Also, theperception of running a finger over a step in the surface can besimulated. This can be achieved, for example, by switching on the signalfor only a short period of time as the user moves their finger over asmall region of the transparent electro-vibration film 10. Thus, theuser will perceive a normal level of friction, followed by an increasedlevel of friction for a short time, which simulates the step, followedby a normal level of friction. In this way it is possible to simulatethe presence of, for example, raised buttons and the like.

It will be understood that by varying the frequency and potential of theelectro-vibration signal and the period of time for which the signal isapplied, the electro-vibration apparatus is fully programmable. Thus, agreat number of different textures and surface profiles can besimulated.

FIG. 4 is a schematic close-up view of the hydrophilic layer 110 of thetransparent electro-vibration film 10. The hydrophilic layer 110comprises a grid, or mesh, of hydrophilic strips 30 provided directlyatop the protective layer 108. The hydrophilic strips may comprise, forexample, strips of titanium dioxide (TiO₂) nano-particles. Thehydrophilic properties of TiO₂ nano-particles can be activated by aphoto-catalytic process. As an alternative, the strips may insteadcomprise another suitably hydrophilic material, such as silicon dioxide,hydrophilic silicones, siloxanes, silanes and other metal organicshaving anti-fog properties.

Moisture on the skin causes the magnitude of electro-vibration sensed bythe user to be significantly reduced, if not completely eradicated. Thehydrophilic strips 30 act to attract and trap moisture from the user'sskin as the finger (or other appropriate body part) is moved along thesurface of the transparent electro-vibration film 10. Thus, the surfaceof the user's finger is dried by the hydrophilic strips as it is movedacross the surface of the transparent electro-vibration film 10. Themagnified view 32 of the hydrophilic layer 110 shows the moisturedroplets 322, for example sweat droplets, having been trapped by thehydrophilic strips 30.

The hydrophilic strips 30 may be approximately 20-50 μm in width andspaced apart by a distance of approximately 0.5-1 mm. It will beunderstood that, unlike in FIG. 4, the hydrophilic strips 30 may not beequidistant, and/or may not form a right-angled grid. For example themesh of hydrophilic lines/strips can be arranged in a pattern similar tothat of a human finger print. This can help to improve sensitivity ofthe user to electro-vibration.

According to alternative embodiments, the hydrophilic strips 30 may beprovided on a substrate comprised of, for example a hard transparentpolymer, which is provided atop the protective layer 108.

The electro-vibration apparatus 1, and in particular the transparentelectro-vibration film 10 is of very simple construction and comprisesno moving parts. Thus, it is relatively easy to manufacture and has arelatively low bill of materials.

Also, the nature of the materials used for the transparentelectro-vibration film 10, and its dimensions, allows the film to bebendable and flexible. Thus, the electro-vibration device can beintegrated with flexible hand-held display devices.

Furthermore, the power used by the electro-vibration apparatus is verylow. This is because the apparatus comprises no moving parts and becausemost of the energy required to provide the electro-vibration simulationis provided by the user as they move their finger across the surface ofthe transparent electro-vibration film 10. For example an electrovibrating film having a size of 10 cm×10 cm has total power consumptionof approximately 20 μW. The energy required to provide feedback to auser of a touch screen display via the electro-vibration apparatus 1 isseveral orders of magnitude lower than that required to provide feedbackusing mechanical and piezo-electric actuators. This is particularlybeneficial for hand-held battery powered devices in which preservingpower is especially important. This is especially true for modernhand-held devices, such as smart phones and the like, which are beingbuilt to perform an ever increasing number of complex functions andoperations, and thus the burden on their batteries is always increasing.

The electro-vibration apparatus 1 also provides benefits to the visuallyimpaired as it allows the user to feel by touch what is being shown onthe display, even if they cannot see it properly. Furthermore dependingon characteristics of the apparatus and at electro-vibration signalfrequencies of higher than 600 Hz, the electro-vibration apparatuscreates a sound while providing electro-vibration to a user. Thefrequency of the sound varies with the frequency of theelectro-vibration signal. This noise can also be of use in providing anindication of what is being displayed on the display screen. Forexample, an icon indicating a music or video player may have aelectro-vibration signal having a frequency above the threshold forproducing noise associated with it. Thus, when the user slides theirfinger over the video/music player icon, a noise will be generated andthis may provide an additional indication to the user as to theidentification of the icon.

FIG. 5 depicts a first exemplary integration of the electro-vibrationapparatus 1 with a hand-held device 50. The hand-held device 50 may be,for example, a mobile phone, a PDA, a GPS receiver or the like. Theelectro-vibration apparatus 1 may be suitable for use with any devicecomprising a display, and optionally also requiring user inputs.

In FIG. 5, the electro-vibration apparatus 1 is integrated with ahandheld device 50. The electro-vibration apparatus 1 is detachable fromthe handheld device 50. The transparent electro-vibration film 10 isprovided atop a display portion (hidden in the Figure) of the device 50.The transparent electro-vibration film 10 may be affixed to the displaypotion of the device via an adhesive layer (hidden) provided on a bottomsurface of the transparent electro-vibration film 10. Alternatively, thetransparent electro-vibration film 10 may be affixed to the displayportion in another suitable way, for example, via a clip mechanism.

The apparatus 1 is electrically connected to the hand-held device 50 bya male-plug connector 52, which connects with a corresponding femaleportion (not shown) of the device 50. The connection may be anyconnection by which power and data may pass, for example but not limitedto, a micro- or mini-USB connection or an audio connection (for instancea headphone socket).

The transparent electro-vibration film 10 is connected to the plugconnector 52 via a wire 54 and a connection hub 56 provided in physicalcommunication with the transparent electro-vibration film 10. Theconnection hub 56 is connected to the contact electrodes 1042 of theconductive electrode layer 104 in any suitable way. Thus, the connectionhub 56 can receive signals from, and pass signals to, the contactelectrodes 1042. The rear electrode 14 is connected to the plugconnector 52 via a second wire 58. The rear electrode can thus receivesignals from the connector plug 52 and/or the connection hub 56. Therear electrode 14 is affixed to the rear of the device 50 in anysuitable way, for example, using adhesive, clips or the like.

Provision of the rear electrode 14 on the rear of the device 50 allowsthe user to hold the device in a natural way, for example, with theirfingers/palms on the rear of the device whilst providing input withtheir thumbs. It will be understood that the rear electrode 14 may belocated anywhere on the device as long as it is in contact the user'sbody when the user is touching the transparent electro-vibration film10.

The feedback processor 16 may be located in any appropriate location,for example, within the housing of the connector plug 52 or in theconnection hub 56. The feedback processor 16 receives data regarding thedisplay via the connection with the device.

The implementation of the electro-vibration apparatus 1 of FIG. 5,allows the apparatus to be removed from the device when it is notrequired by the user. It also allows for existing devices to beintegrated with the electro-vibration apparatus 1.

FIG. 6 shows an alternative integration of the electro-vibrationapparatus 1 with a hand-held device 60. In FIG. 5, the apparatus 1 ispermanently integrated with the device 60, for example duringmanufacture of the device 60.

FIG. 6 is a cross-section through the device 50. Electrical connectionsare schematic only and are shown using dashed lines.

The transparent electro-vibration film 10 of the apparatus is providedatop the display panel 12. The rear electrode 14 is provided on the rearside of the device 60. Again, it will be understood that the rearelectrode 14 may be provided elsewhere on the device 60. Also, the rearelectrode 14 may constitute all or part of the housing 62 of the device.The feedback circuitry 16 is operable to receive power from the battery18 of the hand-held device 50. In the device of FIG. 7, the feedbackcircuitry 16 is integrated with the processor which controls the displaypanel 12 as a single processor. This may be, for example, the mainmicroprocessor which controls the device 60. Alternatively, the feedbackcircuitry 16 may be separate from and may receive data from theprocessor which controls the display.

According to alternative embodiments of the electro-vibration apparatus1, the hydrophilic layer 110 may not be disposed on the surface of thetransparent electro-vibration film 10. Alternatively, as shown in FIG.7, a hydrophilic strip 70, of a similar construction as the hydrophiliclayer 110, may be provided to one side of the display region 72, andthus also of the transparent electro-vibration film 10. This allows auser to dry their finger/thumb etc. on the hydrophilic strip prior totouching the transparent electro-vibration film 10.

Although the electro-vibration apparatus 1 has been described inrelation to portable electronic devices, the skilled person willappreciate that it also has a number of other applications. For example,it may be used dynamically to provide Braille for the visually impaired.Also, it may be used to provide “blind steering for users of electronicdevices. As such, based on the presence/lack of presence ofelectro-vibration, a user of a device can determine without looking atthe display, whether their finger is at an appropriate location on thedisplay. Similarly, the electro-vibration apparatus can be used toindicate to the user that their finger is correctly positioned in, forexample, a fingerprint scanner. The electro-vibration apparatus may alsobe used in relation to computer gaming, in which the current trend istowards authentic human gestures. These may be embellished by amulti-purpose conformal tactile surface, such as can be provided by theelectro-vibration apparatus. Also, due to the thin nature of thetransparent electro-vibration film 10, it may be incorporated with smallobjects in order to provide information to, and receive information fromthe object. Examples of such objects are electronic bank cards and USBmemory sticks. For example, electro-vibration could be used toillustrate to a user the amount of money left on the bank card, or thenumber of files stored on the USB stick. Also, the apparatus may be usedto create 3D tactile images, which may be of particular use for maps andthe like.

In the above-described embodiments, the electro-vibration film iscomprised of plural different layers. However, it will be understoodthat, according to other exemplary embodiments, the electro-vibrationfilm 10 may not include one or more of the hydrophilic layer 110, theprotective layer, the dielectric layer 108, and the substrate layer 102.

As used in this application, the term ‘circuitry’ refers to all of thefollowing:

hardware-only circuit implementations (such as implementations in onlyanalogue and/or digital circuitry); and

to combinations of circuits and software (and/or firmware), such as: (i)to a combination of processor(s) or (ii) to portions ofprocessor(s)/software (including digital signal processor(s)), software,and memory(ies) that work together to cause an apparatus to performvarious functions); and

to circuits, such as a microprocessor(s) or a portion of amicroprocessor(s), that require software or firmware for operation, evenif the software or firmware is not physically present.

This definition of ‘circuitry’ applies to all uses of this term in thisapplication, including in any claims. As a further example, as used inthis application, the term “circuitry” would also cover animplementation of merely a processor (or multiple processors) or portionof a processor and its (or their) accompanying software and/or firmware.The term “circuitry” would also cover, for example and if applicable tothe particular claim element, a baseband integrated circuit orapplications processor integrated circuit for a mobile phone, a cellularnetwork device, or other network device.

It should be realised that the foregoing embodiments should not beconstrued as limiting. Other variations and modifications will beapparent to persons skilled in the art upon reading the presentapplication. Moreover, the disclosure of the present application shouldbe understood to include any novel features or any novel combination offeatures either explicitly or implicitly disclosed herein or anygeneralisation thereof and during the prosecution of the presentapplication or of any application derived therefrom, new claims may beformulated to cover any such features and/or combination of suchfeatures.

The invention claimed is:
 1. A portable display device comprising: anoptically transparent sheet comprising an electrically conductive layer;an electrode element; electro-vibration circuitry connected to theelectrically conductive layer and the electrode element, where theelectro-vibration circuitry is configured to provide a time-varyingvoltage signal across the electrically conductive layer, a body of auser, and the electrode element so as to cause a user to experienceelectro-vibration in a first body part of the user when the first bodypart is moved across an exterior surface of the optically transparentsheet while a second body part of the user is in contact with theelectrode element; and a display panel having a display surface, thedisplay panel being configured to display images to a user via thedisplay surface, wherein the optically transparent sheet is arranged tooverlie at least a portion of the display surface.
 2. The portabledisplay device of claim 1, wherein the electrode element is supported ona housing of the portable display device.
 3. The portable display deviceof claim 2, wherein the display surface constitutes a portion of a frontexterior surface of the device and wherein the electrode element isprovided on a rear exterior surface of the device.
 4. Apparatuscomprising: an optically transparent sheet comprising an electricallyconductive layer; an electrode element; a detector configured to detecta user touch input on the optically transparent sheet; andelectro-vibration circuitry connected to the electrically conductivelayer, the electrode element and the detector, where theelectro-vibration circuitry is configured to provide a time-varyingvoltage signal across the electrically conductive layer, a body of auser, and the electrode element in response to detecting a user touchinput on the optically transparent sheet.
 5. The apparatus of claim 4,comprising a detector configured to determine a location on theoptically transparent sheet of a touch input by measuring parametersrelating to the electrically conductive layer.
 6. The apparatus of claim5, wherein the electro-vibration circuitry is configured to provide thetime-varying voltage signal across the electrically conductive layer andthe electrode element if the location on the optically transparent sheetof the user touch input is coincident with a predetermined location. 7.The apparatus of claim 6, wherein the apparatus further comprises adisplay panel having a display surface, the display panel beingconfigured to display images to a user via the display surface, whereinthe optically transparent sheet layer is arranged to overlie at least aportion of the display surface, and wherein the predetermined locationcorresponds to a location of an object displayed on the display surface.8. A method comprising: detecting a touch input on an opticallytransparent sheet, where the optically transparent sheet comprises anelectrically conductive layer; and in response to detecting a user touchinput on the optically transparent sheet, providing a time varyingvoltage signal across the electrically conductive layer, a body of auser, and an electrode element.
 9. The method of claim 8 furthercomprising: determining a location on the optically transparent sheet ofthe user touch input, by measuring parameters relating to theelectrically conductive layer; comparing the location on the opticallytransparent sheet of the user touch input with one or more predeterminedlocations; providing the time varying voltage signal across theelectrically conductive layer and the electrode element, in response todetermining that the determined location of the user touch input iscoincident with one of the one or more predetermined locations. 10.Computer executable code stored on a computer-readable medium, which,when executed by computer apparatus causes the computer apparatus toperform the method of claim
 8. 11. Apparatus comprising: an opticallytransparent sheet comprising an electrically conductive layer; anelectrode element; and electro-vibration circuitry connected to theelectrically conductive layer and the electrode element, where theelectro-vibration circuitry is configured to provide a time-varyingvoltage signal across the electrically conductive layer, a body of auser, and the electrode element so as to cause the user to experienceelectro-vibration in a first body part of the body when the first bodypart is moved across an exterior surface of the optically transparentsheet while a second body part of the body is in contact with theelectrode element.
 12. The apparatus of claim 11, comprising a detectorconfigured to detect a contact of the first body part on the exteriorsurface of the optically transparent sheet by detecting a current in theelectrically conductive layer.
 13. The apparatus of claim 12, where theelectro-vibration circuitry is configured to provide the time-varyingelectric voltage signal across the electrically conductive layer and theelectrode element in response to the detector detecting the contact ofthe first body part on the exterior surface of the optically transparentsheet.
 14. The apparatus of claim 11 further comprising a contactlocation detector configured to determine a location of contact betweenthe first body part and the exterior surface of the opticallytransparent sheet by measuring parameters relating to the electricallyconductive layer.
 15. The apparatus of claim 14, wherein theelectro-vibration circuitry is configured to provide the time-varyingelectric voltage signal across the electrically conductive layer and theelectrode element if the location of contact between the first body partand the exterior surface of the optically transparent sheet iscoincident with a predetermined location.
 16. The apparatus of claim 11,further comprising a hydrophilic member for removing moisture from thefirst body part.
 17. The apparatus of claim 16, wherein the hydrophilicmember comprises an arrangement of hydrophilic strips.
 18. The apparatusof claim 16, wherein the hydrophilic member constitutes at least aportion of the exterior surface of the optically transparent sheet. 19.The apparatus of claim 11, wherein the optically transparent sheetfurther comprises a layer of dielectric material provided between theelectrically conductive layer and the exterior surface of the opticallytransparent sheet.
 20. The apparatus of claim 11, wherein the opticallytransparent sheet further comprises a layer of scratch-resistantmaterial provided between the electrically conductive layer and theexterior surface of the optically transparent sheet.
 21. The apparatusof claim 1, where the optically transparent sheet comprises a dielectriclayer covering the electrically conductive layer.